This invention relates to high temperature process vessels such as furnaces, reactors, containment vessels, cyclones, etc. which are subjected to relatively high temperatures and, more particularly, to such type of vessels in which water cooled spiral coils are provided to reduce the temperature of the vessel.
Certain types of process vessels, such as cylindrical furnaces, cyclone separators or the like, operate at extremely high temperatures, such as 3000.degree. F., and therefore must be designed to continuously withstand the temperature without failing. For example, cyclone separators used in coal gasification, incineration, fuel combustion, calcining, etc., include a gas discharge tube, or vortex finder, located centrally within the cyclone separator and extending into the housing below the top of the separator. Since both the exterior and the interior walls of the discharge tube are exposed to extremely high temperature conditions these walls must be fabricated from materials including a commercially available ceramic or refractory material. However, it is difficult, if not impossible, to construct a gas discharge tube of the above type entirely of such material without encountering structural limitations and support problems. For example, it has been suggested to construct the discharge tube from metallic materials and insulate same on both sides with ceramic or refractory materials. However, this is unsatisfactory since both sides of the tube are exposed to the high temperature and the metal is trapped within the insulation materials and is subjected to the high temperature on both sides. Thus, the metal can reach its molten temperature and fail structurally. Other attempts to cope with this problem include designs having water-cooled tangent tubes in front of the refractory or internal vessel heads, fluidization grids, cyclone throats, etc. However, each of these designs gives rise to other problems, such as inadequate sealing, poor support and short life spans.